Teas, both green and black teas, contain caffeine, but the caffeine in these drinks does not appear to be as physiologically available as in coffee. In fact, green tea is believed to have a relaxing benefit owing to the flavanols (i.e., the catechins and epicatechins) present in green tea. Green tea has had several other physiological benefits attributed to it. It is believed to lower blood pressure and to have other soothing and healing benefits. It is believed that the flavanols are responsible for these benefits.
The catechins and epicatechins, also known as flavanols, are obtained by the extraction of plants, e.g. green tea and related plants. Plants containing catechins are known to those skilled in the art. These flavanols are natural substances present in a variety of plants including green teas and herb teas.
Green tea includes materials obtained from the tea plant Camellia sinensis, for instance, freshly gathered tea leaves, fresh green tea leaves that are dried immediately after gathering, fresh green tea leaves that have been heat treated before drying to inactivate any enzymes present, and aqueous extracts of these leaves. Green tea materials are tea leaves and their extracts which have not undergone substantial fermentation to create black tea.
The flavanols can be extracted from either a single plant or mixtures of plants. Examples of the most common flavanols which are obtained from extraction from the tea plants and other members of the Catechu gambir or (Uncaria family) are catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate.
The flavanols can be extracted from green tea or other natural source by hot water, but then have to be isolated from the water mixture. Up to the present, this isolation has been done in low yield, less than 30%, and through the use of chlorinated solvents, e.g chloroform and methylene chloride. In addition, these solids often have a grassy or green flavor associated with them. The chlorinated solvents remove grassy flavors, but the use of these solvents for materials to be used for human consumption is being questioned.
It has now been found that use of a mixture of solvents which are food approved can satisfy both the deflavoring of the green tea and also isolate the catechins from the water extract. Yields as high as 70% to 80% recovery are achieved.
It has also been found that co-drying these deflavored flavanols with cellulose, pectins, sugars and gums produces a flavanol with a less bitter taste.
Therefore, it is an object of this invention to provide a process for isolating and deflavoring flavanols from green teas and other natural sources.
It is also an object of this invention to provide dried flavanols with a less bitter taste.
These and other objects will become apparent from the description herein.
All percentages are by weight unless otherwise indicated.